Special sense Flashcards
location of general sense organs
- exteroceptors (cutaneous)
- visceroceptors
- proprioceptors (joints, muscles, tendons)
where are osmoreceptors
hypothalamus → detect changes in osmolarity
olfactory R
detect odorant chemical in solutions
- cilia in roof of nasal cavity (olfactory epithelium)
- olfactory bulb/N needs to be covered in mucous to be working
- olfactory centres in temporal lobe → interpretation, integration, memory (limbic system)
- also links to taste
7 qualities pf smell
associated with memory
- pepperminty
- musky
- floral
- ethereal (triggers memory)
- pungent
- putrid
- camphoraceous (moth balls)
taste (gustation)
- salty (rostral lateral) → Na enter cells
- sour (caudal lateral) → senses HCl, H+ enter cells
- bitter (back) → sense quinine
- sweet (tip) → sense sucrose
- umami → ‘meaty/savoury taste’ senses MSG
papillae
- each pap has 1-100 taste buds
- each bud has 50-150 taste cells (are not neurons)
- form synapses gustatory afferent axons → tastants dissolved in saliva binds to R
taste
ANT 2/3 → facial N
POS 1/3 → glossopharyngeal N
- N → medulla → thalamus → taste center in parietal lobe (limbic system to develop memories)
structures of ear
- pinna, tragus (ear lobe)
- ex acoustic meatus → leads to tympanic membrane
- mid ear bone → malleolus, incus, stapes
- eustachian tube → mid ear to nasopharynx (equalises pressure b/w ex and mid ear
- oval window
- inner ear
cochlear
contains organ of corti
- consist of supporting cells and hair cells
how does sound waves vibrate hair cells
sound waves → move endolymph → deform hair cells → open/close channels → AP → cochlear branch of vestibulocochlear N
maintaining static equilibrium
by vestibule
- detects head position in relation to gravity/acceleration when motionless
dynamic equilibrium
semicircular canal
- detection of movement of endolymph in canal
how is hearing impairment established
- poor air conduction (form build up of air cerumen)
- presbycusis → hearing loss associated with ageing (hair cell damage/atrophy)
meniere’s disease
excessive endolymph accumulation → increase pressure that disrupts balance and hearing
fibrous layer of vision
- sclera (white covering eye)
- cornea (outside layer continuous with sclera)
vascular layer
- choroid (BS to eye)
- ciliary body (continuous with choroid, and prod aq/virtreous humour)
- iris (circular muscles controlling size of pupil)
inner layer
retina
- contains optic disc (blind spot → optic N leaves retina)
- fovea → high conc of cones
optic N (no sensory cells are at entry of optic N)
retinal BV
3 types of optic neurons
photoR (rods/cones) → bipolar neurons → ganglion neurons → optic N → occipital lobe
ratio of rods and cones
high rods (B&W) : low cones (colour)
what prevents eyeball from collapsing
vitreous humour
- fills POS cavity
Aq humour
- fills ANT cavity
- prod. by ciliary body
- drained by canal of schlemm
glaucoma
inability to drain aq humour
- damages lens structures
physiology of vision
- processes to focus light (IF
if >6m away
accommodation, constriction, convergence not required
presbyopia
ageing → lose elasticity → inability to bulge and accommodate for near vision
myopia
short-sighted
- image focused in front of fovea
hyperopia
long-sighted
- image focused behind fovea
astigmatism
irregular curvature of cornea (different points of focus on retina)
cataracts
cloudy area within lens due to age-related degeneration
retinal detachment (retinoschisis)
fluid accumulation → seperates retina from underlying tissues (AMD)
